Theorem 3.5 ([1]}, Theorem 9.3) 
For k = 2,3, the \(\vartheta _0\)  coefficient in \(\vartheta _{p_1}\cdots \vartheta _{p_k}\)  is \(\sum _{\textbf {A} \in NE(X)} N_{p_1,\ldots ,p_k,0}^\textbf {A}\ t^\textbf {A}\) .

